The present invention generally relates to hose assemblies and their manufacture. More particularly, this invention relates to processes for securing fittings to hoses to produce hose assemblies, nonlimiting examples of which include rotary hose assemblies, vibration hose assemblies, choke and kill hose assemblies, super choke and kill hose assemblies, and Kelly hose assemblies. As used herein, the terms “hose” and “hose assemblies” refer to any hose, tube or other type of conduit or conduit assembly adapted to transport a fluid (liquid or gas) or protect electrical wiring or other hardware susceptible to damage.
FIG. 1 shows an example of a hose fitting 10 attached to an end of a hose 12. The hose 12 has a relatively large diameter (e.g., exceeding two inches (about 5 cm)) and is part of a high-pressure hose assembly of a type commonly used, for example, by the oil industry. FIG. 11 represents a similar hose 16 as comprising an interior layer 20 (typically rubber or another elastic, flexible or pliable material), a surrounding reinforced intermediate layer 22 (e.g., reinforced with steel wire), and an exterior layer 24 (typically rubber or another elastic, flexible or pliable material) that surrounds the interior and intermediate layers 20 and 22. Processes for attaching hose fittings to hoses of the types represented in FIGS. 1 and 11 are currently performed with hydraulic swaging machines, an example of which is shown in FIG. 2. The industries that utilize rotary and vibration hose assemblies typically use a hydraulic swaging process as it is currently considered to be the most effective manner available. For relatively large-diameter, high-pressure hoses, current swaging machines are not powerful enough to compress a fitting onto the end 18 of the hose 16 with the exterior layer 24 present. Therefore, FIG. 12 represents the end 18 of the hose 16 as having been externally skived to remove the exterior layer 24 before attempting to attach a hose fitting using a swaging process. A common industry method for removing a rubber exterior layer 24 during the skiving process involves manually removal with a machete or similar tool. This process is very laborious and time consuming. For example, it is common for the skiving process to take fifteen minutes or more to remove a rubber exterior layer from each end of a hose, for a total accumulative time of thirty minutes or more of labor per hose.
Once the hose 16 has been prepared as shown in FIG. 12, swaging processes are generally accomplished by loosely assembling a fitting (not shown) onto the skived end 18 of the hose 16, placing the unfastened (unswaged) hose assembly in a swaging machine, and then operating the swaging machine to crush (compress) the fitting with die halves, such that an initial diameter of a portion of the fitting is reduced to a diameter nearly equal to the die halves. More particularly, the swage is created by pushing or forcing the fitting through the die halves that together define a tapered inner diameter. The fitting starts on the larger diameter side of the die halves and is pressed through the die halves toward the smaller diameter side using a large hydraulic cylinder as a ram. As the fitting passes through the die halves, it is compacted and its diameter is reduced to the size of the smaller diameter defined by the tapered die halves. The desired final diameter of the swaged portion of the fitting, in other words, a diameter by which the fitting adequately squeezes the hose 16 to provide a permanent connection, is typically not achieved in a single swage cycle. Instead, the process must typically be repeated two or three times on the same portion of the fitting to reach the desired final diameter, and requires the use of progressively smaller die halves.
FIGS. 3 and 4 represent a hose assembly 30 having a hose fitting 32 swaged to a skived end of a hose 34. As shown in FIG. 3, one end of the hose 34 is received through an opening into an annular-shaped cavity between annular-shaped exterior and interior portions of the fitting 32, and is compressed within the cavity by the exterior portion within the portion 36 of the fitting 32 that has been swaged. As depicted in FIGS. 3 and 4, the portion 36 of the fitting 32 that is swaged is typically a single contiguous surface area or continuous segment of the fitting 32, typically separated from the adjacent unswaged portion of the fitting 32 by a circumferential “bubble” 38 that has a larger diameter than the swaged portion 36. There are no current processes that separate the swaged portion of a fitting into multiple separate (noncontiguous, discontinuous) surface areas or segments.
Though well suited and accepted in the industry, there are a few disadvantages to the current industry swaging methods. A particularly notable disadvantage is the time required to complete a swaging operation, for example, about 45 to 70 minutes per side of a hose assembly of the type represented in FIG. 1. Because each hose assembly typically requires two fittings to be attached at each end, a total time of about 90 to about 140 minutes may be required to assemble a complete hose assembly. This time restraint can significantly limit the total number of completed products that can be produced per day on a swaging machine. As such, another disadvantage of current industry swaging methods is that the desired final diameter cannot typically be achieved in a single swage cycle, such that a swaging machine typically requires multiple sets of die halves to swage a fitting to increasingly smaller diameters until the desired final diameter is achieved. This requirement adds additional time to the swaging process, particularly since the die halves must be removed and replaced between each cycle. Die halves are generally very heavy and difficult to move for an individual employee. Furthermore, the need for an extensive number of die halves increases the cost of purchasing, owning, and operating a swaging machine.
Attempts have been made to produce hose assemblies similar to those represented in FIGS. 1, 3, and 4 with a crimp machine used to crimp, rather than swage, the hose fitting to the hose. Notably, the crimp process relies on different principles than the swage process. As used herein, a crimp is a diametrical radial crushing (compacting) of a hose fitting onto a distal end of a hose to form a permanent connection, as opposed to the aforementioned swaging operation in which the fitting is pushed or forced through a tapered inner diameter defined by die halves. While both processes compress a fitting onto a hose, the crimping process involves moving the crimp dies radially inward into the fitting, whereas the swaging process holds the die halves stationary and pushes the hose through their tapered inner diameter.
Attempts have been made to crimp non-skived hoses and fitting assemblies in a single complete crimp cycle. An example will be described in reference to FIGS. 14A, 14B, and 15, which schematically represent the hose 16 of FIG. 11 assembled with a fitting 14 to form a hose assembly. FIG. 14A represents the fitting 14 loosely assembled on the hose 16 prior to crimping, and FIGS. 14B and 15 represent the result of a crimp machine having compressed (crushed) the fitting 14 onto the hose 16, with the exterior layer 24 (non-skived) still attached to the hose 16. FIG. 15 further identifies a crimp area 15 over which the crimp has been performed, and shows the crimp area 15 as being a continuous portion of the length of the fitting 14. Depending on the diameter of the hose 16 and the type, structure, size, or material of the fitting, the length of the crimp area 15 can be relatively long, for example, about 10 to about 14 inches (about 25 to about 36 cm) long. Notably, FIGS. 14A and 14B represent that crimping processes often cause elongation of the fitting 14 in the lengthwise (axial) direction. While normally negligible in small crimp lengths, for example, about 1 to about 4 inches (about two to about 10 cm) long, this effect may become a problem for long crimp lengths, for example, over about 4 inches (about 10 cm) long. As represented for the particular example of FIGS. 14A and 14B, a 15-inch (about 38 cm) long steel fitting may increase in length during crimping anywhere from about one-half inch to about 2 inches (about 1 to about 5 cm) in the axial direction. As a result of the fitting deformation during the crimping process, the exterior layer 24 (FIG. 11) of the hose 16 is distorted and often damaged. The damaged exterior layer 24 will often exhibit reduced strength and integrity relative to its original condition on the hose 16. This damage may cause premature failure at the connection/interface between the hose 16 and fitting 14 during pressure testing or operation. In one such attempt, the fitting 14 started to slide off the end of the hose 16 before the required test pressure could be achieved during pressure testing.